Systems, methods, and software for improved video data recovery effectiveness

ABSTRACT

Methods, systems, and software are provided herein that allow for storing a data file in a storage device. The storage system splits a video data file into a plurality of data segments, generates a plurality of recovery headers for the data segments, and combines ones of the recovery headers with ones of the data segments to form a plurality of storage packets.

RELATED APPLICATIONS

This patent application is a continuation of U.S. patent applicationSer. No. 14/604,915, filed Jan. 26, 2015, entitled “Systems, Methods,and Software for Improved Video Data Recovery Effectiveness,” which is acontinuation of U.S. patent application Ser. No. 13/253,802, filed Oct.5, 2011, now patented U.S. Pat. No. 8,942,543, entitled “Systems,Methods, and Software for Improved Video Data Recovery Effectiveness,”which claims the benefit of priority to U.S. Provisional PatentApplication No. 61/390,446, filed Oct. 6, 2010, entitled “Systems andMethods for Improving File Recovery Effectiveness,” all of which arehereby incorporated by reference in their entirety.

TECHNICAL FIELD

Aspects of the disclosure are related to the field of video data storageand, and in particular, storing video data with file recoveryinformation on digital storage systems.

TECHNICAL BACKGROUND

Information retention is one of the key functions of modern computing.Digital data is stored so it can be used or accessed again at some laterpoint in time. There are many different storage technologies which areused for long term storage of data files including disk drives, flashmemory, optical discs, tape drives, as well as others. Modern digitalvideo processing systems use these types of storage mechanisms for thestorage of video. In addition to other functions, the systems mustmanage the inventory of video which resides on a storage device as filesare added, changed, deleted, or replaced.

Like most computer systems, many video processing systems typically makeuse of some type of file index to keep track of all the informationpertaining to where files, and portions of files, are located on thestorage device. A digital video file, like other computer files, may besplit up when stored. The different pieces of the file may get stored inmany different locations scattered across the storage device whereverunused space is available. Video processing systems typically use somesort of file index to be able to locate the various pieces of the videofile in order to be able to reassemble the pieces correctly when thefile is retrieved.

Computer systems and computer operating systems manage the inventory ofinformation which resides on a storage device. In the ideal situation,the first data file written to a storage device starts at the firstaddress location and the second data file written to the storage devicestarts at the address location immediately following the end of thefirst data file and the sequence repeats for subsequent data files. Thissimplistic system only works if data files are only written once andnever changed, erased, or replaced. In reality, the distribution of datafiles across the storage device becomes much more complex after datafiles are changed, erased, or replaced. Video processing systems used toview and manipulate video data files operate in a similar manner andface similar challenges with respect to the management of data files.

When a data file is erased, an empty slot of storage space becomesavailable on the storage device. However, this slot is the size of thedata file just erased and a new data file to be stored which is largerthan the slot cannot be stored, in its entirety, in the slot. Similarly,a data file which was previously stored in a slot on the storage deviceand is now modified in a manner which makes the file bigger will nolonger fit into its original storage slot. Some or all of the data filemust now be relocated to another area of the storage device. For thesereasons, as well as others, most rewritable storage devices are notsequentially populated with complete data files from beginning to end.The storage device eventually ends up being a continuously changingpatchwork of used and unused storage locations.

This situation is further complicated by the fact that data files existin all sizes and the patchwork of unused space on a storage devicecontains spaces of many different sizes. While it is ideal to store adata file in a single segment of contiguous storage space on the storagedevice, this is not always possible because the available slots ofunused storage space are often smaller than the data file itself.Therefore, data files are often broken into segments when they arestored in order to make used of the smaller slots of unused storagespace. There is a significant management task associated with keepingtrack not only of which data files are on the storage device and wherethose data files are located on the storage device but also keepingtrack of where each of the pieces of a data file resides if the datafile has been broken into segments during the storage process.

Most computer systems and computer operating systems make use of sometype of file index to keep track of all the information pertaining towhere files, and portions of files, are located on the storage device.One type of file index which is commonly used is a file allocation table(FAT). A file index serves a function similar to that of a table ofcontents in providing detailed information about what data filescurrently reside in the storage device and where they are located.Because the data files may be scattered around the storage device inmany different places and pieces, the file index is critical to findingdata files on the storage device and retrieving them. Digital videofiles, like other computer files, may be split up and scattered aroundin a similar manner. A video processing system must also use some sortof file index to be able to locate and retrieve the various pieces of avideo file and assemble them correctly.

In many systems, when a data file is erased the actual data bits ofinformation on the storage device are not actually erased oroverwritten. Instead, the reference to the data file is simply removedfrom the file index. Without the information about where the pieces ofthe data file are located, it is erased in the functional sense eventhough all of the bits of data still exist on the storage device. Theactual data bits associated with the data file may only get changed oroverwritten when that slot on the storage device is used to store adifferent data file. Similarly, formatting a storage device often onlyinvolves resetting or erasing the file index and the data filesthemselves are unchanged. However, these data files are virtuallyinaccessible because the file index, the map which explains where allthe segments of data are and how they fit together, is gone.

A similar situation may result if some portion of a storage device isdamaged, erased, corrupted, or no longer works properly. If any of thesecircumstances affect the file index or the tools which allow the fileindex to perform its function, it may appear that some or all of thedata files have been erased. In reality, the data files may still existon the storage device but they are inaccessible because the map to wherethe pieces of the data files are located within the storage device isdamaged, corrupted, or erased.

In these situations, it is desirable to have another means of recoveringand reconstructing data files which may still exist on the storagedevice. While the file index is effective as a single, centralizedsource of information regarding the organization of the data files onthe storage device, it is also a central point of risk or failure whichimpacts all of the data on the storage device. For these reasons, it isdesirable to also have information located with the data files orsegments themselves which could aid in the reconstruction of the videodata file if the file index could not be used.

Overview

Methods, systems, and software are provided herein that allow forstoring a data file in a storage device. In a first example, a method ofoperating a storage system is disclosed. The method includes splitting avideo data file into a plurality of data segments, generating aplurality of recovery headers for the data segments, and combining onesof the recovery headers with ones of the data segments to form aplurality of storage packets.

In a second example, a computer-readable medium having programinstructions stored thereon for operating a storage system is disclosed.When executed by the storage system, the program instructions direct thestorage system to split a video data file into a plurality of datasegments, generate a plurality of recovery headers for the datasegments, combine ones of the recovery headers with ones of the datasegments to form a plurality of storage packets, locate empty slots on astorage device for the storage packets, and store the storage packets inthe empty slots.

In another example, a storage system is disclosed. The storage systemincludes a processing system configured to split a video data file intoa plurality of data segments, generate a plurality of recovery headersfor the data segments, and combine ones of the recovery headers withones of the data segments to form a plurality of storage packets, andlocate empty slots on a storage device for the storage packets. Thestorage device is also configured to store the storage packets in theempty slots.

BRIEF DESCRIPTION OF THE DRAWINGS

Many aspects of the disclosure can be better understood with referenceto the following drawings. The components in the drawings are notnecessarily to scale, emphasis instead being placed upon clearlyillustrating the principles of the present disclosure. Moreover, in thedrawings, like reference numerals designate corresponding partsthroughout the several views. While several embodiments are described inconnection with these drawings, the disclosure is not limited to theembodiments disclosed herein. On the contrary, the intent is to coverall alternatives, modifications, and equivalents.

FIG. 1 is a system diagram illustrating system 100;

FIG. 2 is a flow diagram illustrating a method of operating a storagesystem;

FIG. 3 is a flow diagram illustrating a method of operating a storagesystem;

FIG. 4 is a system diagram illustrating system 400;

FIG. 5 is a flow diagram illustrating a method of operating a storagesystem; and,

FIG. 6 is a flow diagram illustrating a method of operating a storagesystem.

DETAILED DESCRIPTION

Provided herein are solutions that allow data files to be stored tostorage systems which improves the ability to reconstruct the data fileswithout the file index information. Information used to locate variouspieces of a data file within a storage system and link the pieces backtogether to reconstruct a data file is typically available within a fileindex, such as a file allocation table (FAT). In the systems, methods,and software described herein, recovery information is included in arecovery header stored with each of a number of pieces of data files toassemble the associated data pieces together to form the data fileswithout any information from a file index. Thus, it possible toreconstruct the data files even though an index file is missing,destroyed, or otherwise unusable.

As a first example, FIG. 1 is a system diagram illustrating system 100.System 100 includes storage system 110 and input device 120. Storagesystem 110 and input device 120 communicate over link 130. Storagesystem 110 includes data 112. Storage system 110 can receive data filesor other computer-readable data over link 130 for storage as data 112.

FIG. 2 is a flow diagram illustrating a method of operation of storagesystem 110. The operations of FIG. 2 are referenced hereinparenthetically. FIG. 2 illustrates a storage operation for storing databy storage system 110. In FIG. 2, storage system 110 receives (201) datafor storage from input device 120. Storage system 110 splits (202) thedata into segments. Storage system 110 finds (203) a storage slot forstorage of the data, and determines (204) if the storage slot is largeenough for the segment and recovery headers associated with the data. Insome examples, the storage slot comprises an empty continuous physicalblock slot, such as a contiguous portion of a storage medium which canfit the segment and associated headers. If the storage slot is not largeenough, storage system finds another storage slot. If the storage slotis large enough, then storage system 110 writes (205) recovery headersassociated with the segment to the storage slot and writes (206) thesegment to the storage slot. If further segments have yet to be stored(207), then storage system 110 finds (203) further storage slots for thefurther segments. However, if all of the segments of the data have beenwritten (208), then the storage process concludes having stored thedata.

FIG. 3 is a flow diagram illustrating a method of operation of storagesystem 110. The operations of FIG. 3 are referenced hereinparenthetically. FIG. 3 illustrates a data recovery operation forretrieving data previously stored by storage system 110. In FIG. 3, arecovery is started (301) by storage system 110. The recovery operationcould be initiated by a user of storage system 110, or in response to adata storage device or storage medium of storage system 110 beingformatted or erased, among other operations. Storage system 110 scans(302) for a recovery header. If a recovery header is found (304), thenstorage system 110 recovers (305) a segment of the data previouslystored. The process repeats as more segments of the data are found byscanning (302) and discovering (304) recovery headers until no morerecovery headers are found (303). In further examples, the segmentsfound associated with the recovery headers are reassembled into a datafile or multiple data files.

Returning to the elements of FIG. 1, storage system 110 could comprisemicroprocessor and other circuitry that retrieves and executes operatingsoftware to operate as described herein. The operating software couldinclude computer programs, applications, logs, firmware, or some otherform of machine-readable processing instructions. When executed bystorage system 110 the operating software directs storage system 110 tooperate as described herein. Storage system 110 could also comprise anon-transitory computer-readable storage medium for storing datathereon. The computer-readable storage medium could comprisenon-volatile memory, such as a hard disk drive, flash memory, phasechange memory, magnetic memory, tape drive, servers, cloud storagesystems, or other non-volatile memory. Storage system 110 also includesdata 112, which could be stored on a computer-readable storage medium ofstorage system 110. Data 112 comprises the data transferred by inputdevice 120, and could include associated segments and recovery headers.

Input device 120 could comprise a data source or data transfer system.Input device 120 could include data source systems, such as user inputsystems, multimedia capture devices, video capture devices, networksystems, computer systems, end-user data systems, or other data sourcesystems. Input device 120 could also include data transfer systems, suchas transceivers, routers, switches, or other data transfer systems,including combinations thereof.

FIG. 4 is a system diagram illustrating system 400. System 400 includesvideo storage system 401 as an example of storage system 110 found inFIG. 1, although storage system 110 could use other configurations.System 400 also includes video source 450 as an example of input device120 as found in FIG. 1, although other input devices could be employed.Video source 450 and video storage system 401 communicate over one oflinks 441. Further input devices, such as video sources, could beemployed and configured to communicate over other ones of links 441.

Video storage system 401 includes communication interface 410,processing system 420, and user interface 430. Communication interface410, processing system 420, and user interface 430 are shown tocommunicate over a common bus 440 for illustrative purposes. It shouldbe understood that discrete links could be employed, such as data links,power links, video links, or other links. Video storage system 401 maybe distributed among multiple devices that together form the elements ofFIG. 4.

Communication interface 410 includes circuitry and equipment to receiveand store video data or other data from a plurality of video sourcesover links 451. Communication interface 410 could comprise networkinterfaces, transceiver circuitry, buffers, video data processors, orother circuitry and equipment. In typical examples, communicationinterface 410 receives digital video from cameras in a digital format,such as MPEG, H.264, Flash, VP8, or JPEG video, and could includevarious packet formats such as IP packets or Ethernet, or other digitalvideo and packet formats. Communication interface 410 could encode,transcode, compress, or encrypt the video into a digital format, orchange a digital format of the video to a different format. In furtherexamples, communication interface 410 receives analog video from camerasin an analog format, such as NTSC, PAL, or other analog video format,and encodes the analog video into a digital format for storage. In someexamples, portions of functionality mentioned above for communicationinterface 410 are handled in processing system 420. Links 441 could usevarious protocols or communication formats as described herein for link130, and could include Ethernet, Internet protocol (IP), video, digital,packet, or other links and protocols, including combinations,variations, or improvements thereof.

Processing system 420 includes storage system 421. Processing system 420retrieves and executes software 423 from storage system 221. In someexamples, processing system 420 is located within the same equipment inwhich communication interface 410 or user interface 423 are located. Infurther examples, processing system 420 comprises specialized circuitry,and software 423 or storage system 421 could be included in thespecialized circuitry to operate processing system 420 as describedherein. Storage system 421 could include a non-transitorycomputer-readable medium such as a disk, tape, integrated circuit,server, flash memory, phase change memory, magnetic memory, opticalmemory, or some other memory device, and also may be distributed amongmultiple memory devices.

Software 423 may include an operating system, logs, utilities, drivers,networking software, and other software typically loaded onto a computersystem. Software 423 could contain application programs, video editingand configuration programs, server software, firmware, or some otherform of computer-readable processing instructions. When executed byprocessing system 420, software 423 directs processing system 420 tooperate as described herein, such as receive data for storage, store thedata in segments on a storage medium with recovery headers, find therecovery headers on the storage medium, and reconstruct the data fromthe segments and the recovery headers, among other operations.

Storage system 421 also includes video storage 422. Video storage system410 receives the video data as transferred by video source 450 andstores the video data on a computer-readable medium such as videostorage 422. In this example, video storage 422 includes several datasegments, with stored segments indicated in grey and unused orpreviously deleted storage space indicated in white. Video storage 422is merely exemplary and other configurations could be shown.

User interface 430 includes equipment and circuitry for receiving userinput and control, such as for receiving instructions for storing,manipulating, deleting, formatting, or recovering data, among otheroperations. Examples of the equipment and circuitry for receiving userinput and control include a mouse, keyboard, push buttons, touchscreens, selection knobs, dials, switches, actuators, keys, pointerdevices, microphones, transducers, potentiometers, accelerometers,non-contact sensing circuitry, or other human-interface equipment. Userinterface 430 could also include a display or other indicator tocommunicate information to a user of video storage system 101, such asmonitors, televisions, projectors, indicator lights, lamps,light-emitting diodes, or other display equipment. It should beunderstood that user interface 430 could comprise a network-based userinterface, such as a terminal shell or other maintenance and controlinterface.

Bus 440 comprises a physical, logical, or virtual communication link,capable of communicating data, video information, or control signals,along with other information. In some examples, bus 440 is encapsulatedwithin the elements of communication interface 410, processing system420, or user interface 430, and may be a software or logical link. Inother examples, bus 440 uses various communication media, such as air,space, metal, optical fiber, or some other signal propagation path,including combinations thereof. Bus 440 could be a direct link or mightinclude various equipment, intermediate components, systems, andnetworks. Bus 440 could be a common link, shared link, or may becomprised of discrete, separate links.

System 400 also includes video source 450. Video source 450 illustratesan example of a device used to capture video data. Video source 450includes lens 452, sensor 454, processor 456, memory 458, andcommunication interface 459. Processor 456, memory 458, andcommunication interface 459 each communicate over bus 442, althoughdiscrete links could be employed. Lens 452 is configured to focus animage of a scene on sensor 454. Lens 452 may be any type of lens,pinhole, zone plate, or the like able to focus an image on sensor 454.Sensor 454 then digitally captures these images and transfers them toprocessor 456 in the form of video. Processor 456 may store some or allof the video in memory 458 in the short term, but eventually processesthe video, and sends the processed video as video data for storagethrough communication interface 459 and link 441. The video data couldinclude MPEG, H.264, Flash, VP8, JPEG video, among other digitalformats, and could be transferred in a packet format, such as Ethernet,IP, or other packet formats, including combinations, variations, orimprovements thereof.

FIG. 5 is a flow diagram illustrating a method of operating videostorage system 401. The operations in FIG. 5 are referenced hereinparenthetically. In FIG. 5, video storage system 401 receives (501) datafor storage from an input device. In this example, communicationinterface 410 receives video data over link 441 from video source 450.The video data could include data packets, a data file, or streamingdata, among other data. Communication interface 410 transfers the videodata for processing and storage over bus 440. In this example, two videodata files are used for illustrative purposes. It should be understoodthat the operations described herein could be applied to other dataformats, content, and arrangements.

Video storage system 401 splits (502) the video data files intosegments. Processing system 420 could process the video data files tobreak the data into several pieces, or segments. In some examples, thedata is received in discrete files, or data packets are combined tocreate a data file. The data file merely represents a collection ofdata, such as a document, video clip, song, or other discrete datacollection. The segments of the data could be segments of the data filesas received or created by video storage system 401. A size of eachsegment could vary. In examples where a predetermined segment size isemployed, the segments could all be of the same size, except for a finalsegment of a data file, which could vary if the remaining data in afile—after being broken into several equal-sized segments—does not alignwith the preferred segment size. In other examples, the segment sizecould vary according to the data content of the data file. For example,if video data is used, then the segment size could be based on a timeduration of the video, such as every one second of video or apredetermined number of video frames would be included in each separatesegment. Variable video compression and encoding techniques may createdifferent sized segments for various equal-time portions of the video.

If all segments of the data have been stored (503), then the processdescribed in FIG. 5 is complete (504). However, since this is theinitial pass for storing the data, then video storage system 401 finds(505) a storage slot for a first segment of the data associated with thefirst data file. The storage slot is found on a computer-readable mediumused for storing data, which in this example includes video storage 422on storage system 421. As shown in FIG. 5, an initial state 580illustrates a state of video storage 422 prior to the operations of FIG.5. In this example, initial state 580 includes two portions of usedspace, namely used spaces 571-572, two portions of free space, namelyfree spaces 578-579, and two portions of old data, namely old data 573.Used spaces 571-572 could include currently stored data, or couldinclude operating system files, protected files, or other data portions.Free spaces 578-579 include storage location which are not currentlyholding data, and can be used to store new data. Old data 573 includesdata segments stored from a previous storage operation which remain onvideo storage 422 after a previous deletion or formatting operation wasperformed. The previous deletion or formatting operation includesmodifying a file index, such as a file allocation table, to clear arecord of the data from the file index without actually modifying thedata segments previously stored.

In this example, free spaces 578-579 and old data 573 could beidentified as potential storage slots for new segments of data. Videostorage system 401 then identifies a portion of the potential storageslots as a storage slot for the first segment of the data associatedwith the first data file. If the storage slot is large enough for thefirst segments of the data as well as an associated recovery header forthe first segment, then the storage slot is selected (506). However, ifthe storage slot is not large enough, then a different storage slot isselected.

Video storage system 401 writes (507) the recovery header into theselected storage slot, as well as writes (508) the segment into the slotwhich is associated with the recovery header. The process above isrepeated for each segment of each data file. As shown first storagediagram 581 in FIG. 5, the first video data file has been written as twosegments with associated recovery headers. The first segment includes‘DATA 1’ as the data segment portion, and preceding information as therecovery header. The recovery header information is discussed in moredetail below. The second segment includes ‘DATA 2’ as the data segmentportion, and preceding information as the recovery header. In thisexample, the first segment and recovery header fit into free space 578,while the second segment and recovery header fit into free space 579.Thus, the first video data file is written as two non-contiguoussegments with associated recovery headers.

As shown second storage diagram 582 in FIG. 5, the second video datafile has been written as two segments with associated recovery headers.The first segment includes ‘DATA 3’ as the data segment portion, andpreceding information as the recovery header. The recovery headerinformation is discussed in more detail below. The second segmentincludes ‘DATA 4’ as the data segment portion, and preceding informationas the recovery header. In this example, the first segment and recoveryheader fit into free space 579, while the second segment and recoveryheader fit into free space 578. It should be noted that old data 573 wasincluded in the potential storage space or storage slots for the newdata, and thus the first segment of the second data file is written toas to overlap a portion of old data 573. Thus, the second video datafile is written as two non-contiguous segments with associated recoveryheaders.

In this example, each segment of data is combined with a recovery headerto form a storage packet. The recovery header is determined by videostorage system 401 during the data storage process. Video storage system401 writes a recovery header into selected slot, where the recoveryheader includes information associated with the first segment as well asthe first data file. Information used to locate the various segments ofa data file within a storage device, such as storage system 421, andlink the segments back together properly to reconstruct the originaldata file is usually available within a file index, such as a fileallocation table. In this example, recovery information is included in arecovery header stored with each data segment such that it is possibleto find and link the data segments together to form the data filewithout any information from the file index. Thus, the method describedherein makes it possible to reconstruct the data file even though a fileindex file is missing, destroyed, or otherwise unusable.

The recovery information includes many pieces of information, such asmetadata, associated with both a single segment of data as well as withall segments for a data file. The recovery information includes, in thisexample, at least five different pieces of information, namely Magicidentifier (ID), Object ID, Sequence Number, Chunk Size, and ErrorDetection Code. Each of these five elements performs a differentfunction which is described in detail below. It should be understoodthat additional or different information could be included in therecovery information.

The Magic ID element is a numerical identifier used to localize astorage packet. If the file index in a storage device is not available,the storage packets are searched to locate the Magic IDs. The Magic IDvalue must not be too simple otherwise the chance of a random occurrenceof the Magic ID sequence could be too high in the data creating falsepositive triggers during a search process. The Magic ID is determined asa large enough value such that it will not appear as part of the storeddata or randomly, but not so large to cause unnecessarily large overheadin the storage packets. In this example, the Magic ID is ‘0xBEEF’ asindicated in the recovery header of each storage packet in first storagediagram 581 and second storage diagram 582. The Magic ID is unique so asnot to be confused with random data or data of the segments. Therefore,in this example a common Magic ID is used for all storage packets. If asecond storage volume was employed, or a storage system comprisingmultiple filesystems, then the Magic ID could vary for each storagevolume or for each filesystem.

While the Magic ID gives the ability to find the storage packets in thestorage device, the Object ID offers a mechanism to identify objectswithin each storage packet. Using the Magic ID and the Object ID, allthe storage packets needed to reconstruct an object can be found in thestorage device. The Object ID must be kept unique even before and aftera format of the storage device. Otherwise, confusion may occur betweenobjects from previous and current format. The Object ID may also becomprised of two different elements. The Primary Object ID and theFormat ID. The Format ID identifies indicates which data is associatedwith which format or wipe of the storage device. The Format ID couldcomprise a counter which increments every time a format of the storagedevice occurs. The Primary Object ID is reset to zero each time a formatoccurs and increases when a new object is stored. A unique Object IDcould be created by combining the Primary Object ID and the Format ID.In FIG. 5, the Object ID is formed by a ‘U’ representing the PrimaryObject ID and an ‘F’ representing the Format ID. Thus, for the firstfile written, where a file corresponds to an object, the first segmenthas “U:1 F:2” as the Object ID, and the second segment also has “U:1F:2” as the Object ID. The ‘F’ parameter indicates the new data isstored after a second formatting of the storage device has occurred,indicated by ‘2’. As shown with old data 573, the ‘F’ parametercorresponds to an earlier formatting, namely ‘1’. The ‘U’ parameterindicates the first data file is the first file written after the secondformatting, namely ‘1’. Each segment associated with the first file willhave the same ‘U’ and ‘F’ parameters in this example. For the secondfile written, the first segment has “U:2 F:2” as the Object ID, and thesecond segment also has “U:2 F:2” as the Object ID. As with the firstfile, the ‘F’ parameter indicates the new data is stored after a secondformatting of the storage device has occurred, indicated by ‘2’. The ‘U’parameter, however, indicates the second data file is the second filewritten after the second formatting, namely ‘2’.

The Sequence Number element of the recovery information provides theability to order the storage packets within a specific object, such asto reconstruct a file from several segments. Even though all the storagepackets in an object may be found using the Magic ID and Object IDheader elements, the storage packets could be in a random order andtheir relationship to each other would need to be determined. Tore-create the original object, the segments are ordered according to theSequence Number associated with each storage packet. In FIG. 5, thesequence number is indicated by an ‘S’ in the recovery headers, and isincremented for each data segment of a single file, and reset for eachnew file. Thus, for the first data segment of the first data file, ‘S’corresponds to ‘1’ and for the second data segment of the first datafile, ‘S’ corresponds to ‘2’. Likewise for the first data segment of thesecond data file, ‘S’ corresponds to ‘1’ and for the second data segmentof the second data file, ‘S’ corresponds to ‘2’.

A header element indicating the Chunk Size is also employed. In mostcases, storage packets will not be contiguous in the storage device.Therefore, unused storage space which contains junk or unwanted data mayimmediately follow data of interest for a segment. However, withoutknowing the size of the data segment, it may be difficult to determinewhen the data segment of interest ends and when the junk data starts.Therefore, the Chunk Size element indicates the expected size of thedata segment. In FIG. 5, a Chunk Size element is not shown for clarity,and instead a graphical indication of the segment sizes is indicated bya relative size of the associated box for each segment. A Chunk Sizeelement could be included, however, which indicates a numerical size,such as in bits or bytes, of the associated segment.

An Error Detection Code is also used to ensure the data or header havenot been corrupted. If there has somehow been corruption in this area ofthe data storage device, the recovery process may recover faulty data.The Error Detection Code could be used to detect faulty recoveryheaders, or to validate the recovery headers or associated datasegments. In further examples, the Error Detection Code includes anerror correction code, or other data correction information, toreconstruct or recover faulty portions of the data segments. Forexample, a cyclic redundancy check (CRC) could be performed on the datato check for faulty data. In FIG. 5, an Error Detection Code element isnot shown for clarity. However, it should be understood that an ErrorDetection Code element could have been included. Examples of ErrorDetection Code include an ECC information, forward error correction(FEC) information, CRC information, checksums, or other error detectionand correction code information.

In the examples above, the recovery information is stored in recoveryheaders which are each stored at the beginning of and contiguous withthe associated data segments, to form the aforementioned storagepackets. It should be understood that other physical relationshipsbetween the storage location of the recovery header information and thestorage location of the data segment may exist and still fall within thescope of the invention.

FIG. 6 is a flow diagram illustrating a method of operating videostorage system 401. The operations in FIG. 6 are referenced hereinparenthetically. In FIG. 6, a recovery is performed in response to aformatting of a computer-readable storage medium, such as video storage422 of FIG. 4. Other examples include a recovery in response to acorruption, loss, unavailability of a file index associated with acomputer-readable storage medium. Video storage system 401 thus startsthe recovery (601) and scans (602) the associated storage system orcomputer-readable medium for recovery headers associated with datasegments previously stored thereon. The scan operation could beperformed by reading the entire computer-readable storage medium andsearching for recovery flags associated with recovery headers storedthereon. The recovery flags in this example include the Magic IDs,although other recovery flags could be employed. In other examples, onlya portion of the computer-readable storage medium is scanned, such as anundamaged portion to discover the recovery headers of associatedrecovery flags.

If no recovery flags are found (603) then no data segments are found(604), and the process terminates. However, if a recovery flag is found,then the recovery header and associated data segment is read orretrieved from the computer-readable storage medium, and an error checkis performed (605). The error check determines if the recovery header orassociated data segment has been damaged, is faulty, or otherwise hascorrupted data associated therewith. Various error checking could beperformed to validate the associated storage packet portions, such as aCRC, ECC operation, or other error detection methods discussed herein.Additionally, if faulty data is found, then an error correction processcould occur to attempt to repair the faulty data. If the error checkfails, then the recovery header or the associated data segment isassumed to be unrecoverable, and the process continues by looking forfurther recovery flags on the computer-readable storage medium. However,if the error check succeeds, then the segment of data associated withthe recovery flag and recovery header is recovered. Further segments arethen scanned for on the computer-readable storage medium. In someexamples, the error check is only performed on the recovery header andnot the data segment. For example, errors in the data segments may notbe critical to data segment recovery, whereas errors in the recoveryheader could be more sensitive to data segment recovery. Also, in thisexample, a file index, such as a file allocation table, is not processedor referenced when scanning for the recovery flags or headers, or toretrieve the headers and segments from the computer-readable storagemedium.

FIG. 6 shows storage device content 680 as a present state of thecomputer-readable storage medium used to store data segments, such asthat used in FIG. 5. Storage device content 680 includes five datasegments and associated recovery headers, and these are indicated belowstorage device content 680 in FIG. 6. The recovered data segments andassociated recovery headers are then grouped into three groups, eachgroup associated with a potential data object, such as a data file. Thefirst potential data object is indicated by the ‘1’ and includes twodata segments namely ‘DATA 1’ and ‘DATA 2’. The second potential dataobject is indicated by the 2′ and includes two data segments, namely‘DATA 4’ and ‘DATA 3’. The third potential data object is indicated bythe ‘3’ and includes one data segment, namely ‘DATA Y’. These recovereddata segments, although associated with a potential data object, are notyet ordered.

The recovered data segments are identified on the computer-readablestorage medium by scanning for the ‘0xBEEF’ Magic ID. Then theassociated recovery header information is found along with a potentialdata segment. A size indicator, such as a Segment Size element, includedin the recovery header indicates how many data bits or bytes are to beincluded in the potential data segment. Additionally, each recoveryheader has an Object ID to indicate with which file or object thesegment or segments are associated, and thus the five recovered segmentsare organized according to this Object ID, once found using the MagicID. Although a first segment of the old data 573 indicated in FIG. 5 ispartially included in storage device content 680, this partial segmentdoes not meet the scan threshold, namely the Magic ID is not completeand thus the recovery flag and header are not found, even though asecond segment of the old data 573 is found.

The recovered data segments are then reassembled by reordering into dataobjects, such as files. In potential data object ‘1’, the SequenceNumber elements of the recovery headers are used to order the datasegments into first data file 681. In potential data object ‘2’, theSequence Number elements are used to order the data segments into seconddata file 682. However, in potential data object ‘3’, the single datasegment does not include all the segments of a complete data object, asindicated by the non-contiguous Sequence Number. Thus, orphan data file683 is determined. Since the data segment associated with orphan datafile 683 is also associated with a previous formatting of thecomputer-readable medium, the data segment may be ignored. In otherexamples, the orphan data segment may be recovered and analyzed foruseful data as a partial file.

In the examples above, a storage slots is located before a storagepacket is transferred to a storage device for subsequent storagethereon. To locate storage slot, a storage device, such as a hard diskdrive, could locate a storage slot comprising a contiguous portion ofusable space on the storage medium, and report an identifier of thecontiguous portion to a storage processing system. The identifier couldinclude an address, block identifier, or other storage locationidentifier. Free storage slot location is used to ensure a storagepacket is not further broken or fragmented into pieces once transferredfor storage on a storage medium. Thus, cooperation with a storage mediumor storage medium controller portion of a storage device may be neededto properly locate free storage slots for storage packets.

In further examples, the operation of locating free storage slots couldbe avoided. In examples of some storage devices, a storage medium isaddressable in predetermined and fixed portions, such as blocks. In someexamples, the blocks are a minimum addressable size of storage units fora storage medium. The storage packets described herein could be sizedaccording to the block size of the storage medium, or anotherpredetermined size. Thus, the data objects or data files are broken upor split into predetermined sizes based on the block sizes for thestorage medium. In this manner, discovery of storage slots with enoughcontiguous free space for a storage packet may not be necessary, as thestorage packets would be sized according to the block sizes, and thuswould not be further broken or fragmented up by a storage mediumcontroller or storage medium when stored thereon.

Although the descriptions, embodiments, and figures discussed hereinprovide examples of using the invention with video files, it should beunderstood that the systems and methods provided for storing andrecovering data will work equally well for many other types of computerfiles and data files. As a result, the invention is not limited to usewith video data or video files.

The included descriptions and figures depict specific embodiments toteach those skilled in the art how to make and use the best mode. Forthe purpose of teaching inventive principles, some conventional aspectshave been simplified or omitted. Those skilled in the art willappreciate variations from these embodiments that fall within the scopeof the invention. Those skilled in the art will also appreciate that thefeatures described above can be combined in various ways to formmultiple embodiments. As a result, the invention is not limited to thespecific embodiments described above, but only by the claims and theirequivalents.

What is claimed is:
 1. A method of recovery of a storage system inresponse to a corruption, loss, or unavailability of a file index, themethod comprising: scanning the storage system for a recovery flag,wherein the recovery flag is common among storage packets to identifyrecovery headers associated with the storage packets; reading therecovery headers and associated data segments from the storage systemfor the storage packets in which the recovery flag is found; groupingthe associated data segments into data object groups, wherein each ofthe data object groups includes a subset of the recovery headers and acorresponding subset of the associated data segments, wherein the subsetof the recovery headers each include common Object ID that uniquelyidentifies a data object on the storage system; reassembling dataobjects stored on the storage system by reordering the correspondingsubset of associated data segments for each of the data object groupsbased on a Sequence Number in the subset of the recovery headers thatspecifies an order of the corresponding subset of associated datasegments to re-create the data object without any information from thefile index.
 2. The method of claim 1, further comprising: identifying anorphan data object for one of the data object groups where the subset ofassociated data segments does not include all data segments of acomplete data object based on the subset of recovery headers indicatinga non-contiguous Sequence Number.
 3. The method of claim 1, wherein therecovery headers each include a Chunk Size that indicates a size of anassociated data segment for reading the associated data segments fromthe storage system.
 4. The method of claim 1, wherein reading therecovery headers from the storage system further comprises: performingerror checking on the recovery headers based on Error Detection Codeincluded in each of the recovery headers.
 5. The method of claim 1,wherein the Object ID comprises a Format ID, wherein the Format IDcomprises a counter which increments each time a format of the storagesystem occurs.
 6. The method of claim 5, wherein the Object ID comprisesa Primary Object ID, wherein the Primary Object ID comprises a counterthat increments when a new data object is stored in the storage systemand resets to zero each time a format of the storage system occurs.